1. Field of the Invention
The present invention relates to a system for detecting a magnetic flux.
2. Description of the Related Art
Such systems are generally known, e.g., from the published German patent document DE 44 42 441 A1 and published European patent document EP 1 052 519 B1, systems of the so-called fluxgate type are known, which have a semiconductor substrate, an excitation element, two detection coils, and a magnetic core. The excitation element includes a coil, which is operated using an alternating current featuring an excitation frequency. The magnetic flux density B in a ferromagnetic material is defined by the strength of the surrounding magnetic field H. A magnetic flux in accordance with the magnetic hysteresis curve (B-H-curve) having the same frequency as the excitation frequency of the alternating current is generated in the magnetic core. The magnetic flux in the magnetic core is proportional to the product from magnetic permeability μ and field strength H of the magnetic field. The permeability is very low in the saturation range, whereas it is very high in the zero crossing of the hysteresis curve. Due to the non-linearity of the permeability, an external magnetic field causes a distortion of the magnetic flux, which is detectable with the aid of the detection coil. In the absence of an external magnetic field, the induced currents in the detection coils are equal to zero. However, if an external magnetic field is present, then the induction currents have different harmonics of the excitation frequency. The sum of the induction currents is not equal to zero and thus a measure for the strength of the external magnetic field.
In the published German patent document DE 44 42 441 A1, a detection system made up of a flux-generating coil, a flux-conducting structure, and a flux-detecting component is described. The flux-generating coil, the flux-conducting structure as well as the flux-detecting component are realized in a plurality of layers on a substrate, the flux-generating coil and the flux-detecting component being spatially separated from each other, and no system such as it is provided in the case of windings that are interlaced with one another (corresponding to two coil systems wound with one another) being present.